Marine sponges prefer Integrated Multitrophic Aquaculture (IMTA) environments for growth: insights from experimental rearing trials in the Mar Grande of Taranto (Mediterranean Sea)

Integrated Multi-Trophic Aquaculture (IMTA) systems represent a sustainable approach to mitigating environmental impacts and enhancing mariculture productivity. This study evaluated the survival and growth of four Mediterranean demosponges— Aplysina aerophoba , Geodia cydonium , Hymeniacidon perlevis , and Sarcotragus spinosulus —reared in an IMTA facility within the Mar Grande of Taranto (Ionian Sea, Italy), compared to a nearby control site. Two rearing cycles were implemented: a short-term (12 months, April 2021–March 2022) and a long-term (18 months, April 2023–October 2024) experiment. Sponge explants were monitored for survival, volumetric growth, and Specific Growth Rate (SGR). Results showed significantly higher biomass increases for most species in IMTA conditions than in the control site, suggesting a possible positive influence of nutrient-enriched environments. A. aerophoba demonstrated the highest performance, achieving up to 489% biomass increase over 18 months, whereas H. perlevis exhibited strong seasonal growth patterns but high mortality outside the IMTA system. Conversely, G. cydonium and S. spinosulus showed moderate but consistent growth. Overall, IMTA conditions were associated with enhanced sponge performance in a species-specific manner, with the clearest benefits for A. aerophoba (growth) and H. perlevis (survival). These findings support the potential of sponges as bioremediators and as a sustainable biomass source for bioactive compounds, restoration, and aquaculture diversification.